Pharmaceutical, biological, biochemical, or biotechnological processes are increasingly performed by means of so-called disposable process solutions—for example, in processing systems in single-use technology. Such processing systems comprise pipelines or reactors, which are designed as disposable containers, e.g., disposables or disposable bioreactors or single-use bioreactor or single-use component. Such disposable containers may, for example, be flexible containers, such as pouches, tubes, or fermenters. Bioreactors or fermenters frequently have supply and discharge lines, which are designed as tubes, for example. Stiff pipe sections may also be used in the supply and discharge lines. After a process is completed, the disposable containers may be disposed of. In this way, extensive cleaning and sterilization processes are avoided. The use of disposable containers in particular prevents the risk of cross-contaminations and thus increases the process reliability.
In order to monitor or control the processes, it may be necessary to measure physical or chemical measured variables of the media contained in the disposable process containers. To this end, optical as well as electrochemical—for example, potentiometric or amperometric—sensors or conductivity sensors are used. So-called multisensors have also proven to be advantageous, which are designed to measure several different measured variables. Such multisensors frequently comprise several sensing elements, wherein each sensing element is designed to detect measured values of one of the measured variables to be monitored.
The processes performed in the disposable containers take place in a closed system, i.e., without any connection to the surroundings outside the disposable container. Since sterile conditions are frequently required, the disposable containers must be sterilized prior to introducing the process media. For this purpose, gamma radiation is frequently used in biochemical, biological, biotechnological, and pharmaceutical applications. Even while the processes are taking place in a disposable fermenter or disposable reactor, the ingress of foreign substances—e.g., seed crystals—from the surroundings into the interior of the disposable container must be prevented, so that the process sequence is not impaired or adulterated. The same also applies to supply and discharge lines, which end in the disposable fermenter or disposable reactor or lead out of the disposable fermenter or disposable reactor.
One or more sensors integrated into the disposable container may be sterilized together with disposable container. As a result of the sterilization and/or in case the disposable containers and the integrated sensors are stored for a longer period of time after sterilization and before commissioning, the properties of the integrated sensors may change, which can result in a change in the respective sensor characteristic curves—for example, to a zero-point drift. Potentiometric and amperometric sensors frequently comprise diaphragms, which should ideally be stored under damp conditions in order to ensure that the sensor outputs reliable measured values immediately after commissioning.
Furthermore, the sterilization by means of gamma radiation required for many biochemical and biotechnological processes may result in the destruction of electronic components of the sensors. It has therefore been proposed, e.g., in DE 10 2011 080 956 A1, to design sensors integrated into the walls of disposable containers to be sterilized as disposable analog sensors and to removably connect them after the sterilization to an electronic unit that is arranged outside the disposable container, comprises non-sterilizable components, and is designed to further process the analog measured values provided by the sensor. After the process is completed, the electronic unit may be used further and may be connected to a new sterilized disposable sensor in a different processing system. Since the complete measuring section, which comprises the analog sensor and the electronic unit, does not exist until commissioning, an efficient calibration, verification, or even an adjustment of the sensors integrated into the disposable containers immediately prior to commissioning would also be desirable in such cases.